DOE must study a volcano blast’s effect on Yucca

Monday, June 25, 2001 | 11:05 a.m.

The Energy Department has been ordered to estimate the consequences of a volcanic eruption at a proposed high-level nuclear waste repository at Yucca Mountain.

A Nuclear Regulatory Commission panel, which met in Las Vegas on Friday, told the DOE to calculate radiation exposures to the air, ground water and people. The calculations will be by computer models of an eruption through Yucca.

If DOE's models show danger to people or the environment from a potential volcanic eruption, that would be another obstacle to the construction of a repository, officials said. The DOE had not planned to study that danger.

It was unclear whether the study would delay the DOE's recommendation on Yucca Mountain's suitability to contain the nation's highly radioactive waste. The recommendation to President Bush and Congress is due at the beginning of next year. The new calculations could take weeks or months, officials agreed.

Yucca Mountain, 90 miles northwest of Las Vegas, is the only site being studied to hold 77,000 tons of highly radioactive commercial and defense waste for at least 10,000 years.

The Nuclear Regulatory Commission would have to license a repository before it could open. The DOE is charged with determining whether the site is scientifically suitable. and, if approved, the department will oversee the repository's construction and operation. The DOE's research of the site has cost about $7 billion so far.

UNLV geoscience professor Eugene Smith told the panel before its vote that new evidence of volcanic activity north and southwest of Yucca Mountain shows that an active field of hot magma has surfaced as recently as 20,000 years ago.

The findings show the potential for a volcanic eruption that could disrupt nuclear waste buried inside the mountain in 12,000 containers, Smith said.

DOE researchers maintain that volcanic activity near Yucca occurred more than 10 million years ago and that falling ash built the mountain in layers. Chances of a volcano affecting the site are minuscule, they said.

"I realize what I am saying is very controversial," Smith said, but he urged the DOE to calculate what would happen to the buried waste if magma flared up through the repository.

Although an eruption is unlikely, such a catastrophic event would bring dire consequences, according to Brittain Hill, an NRC consultant and senior research scientist at the Southwest Research Institute in San Antonio.

Hill reported to the Geological Society of America meeting in Reno last November that the greatest radiation risk to people for the first 1,000 years after a Yucca repository is sealed would come from a volcanic eruption.

The Southwest Research Institute is consulting for the Nuclear Regulatory Commission on independent studies of Yucca Mountain.

Peter Swift, a scientist with DOE's chief contractor, Bechtel-SAIC, said that during a volcanic eruption most of the ash would drift south of the repository toward an uninhabited area, a point disputed by the NRC panel.

Noting wind shifts at Yucca Mountain, NRC reviewers told the DOE to calculate radiation doses from inhaling the hot and radioactive particles, from radiation in ground water and from hot volcanic particles delivering radioactive material to people's skin, even if they were inside their homes.

Smith said the latest eruption near Yucca Mountain occurred in Lunar Crater, about 100 miles north, 20,000 years ago. The next was 77,000 years ago at Crater Flat, about 12 to 20 miles west of the site.

The volcanic activity in the Southwest could be linked to a chain of mountain-building volcanoes stretching from Mount St. Helens and Mount Rainier in Washington to Southern Nevada, Smith said.

Based on 1,000 chemical samples taken from deposits near Yucca Mountain and analyzed at UNLV and the University of Kansas, Smith said all of the volcanic debris is younger than 8.5 million years. He then plotted the known eruptions in the area that showed periodic volcanic activity.

The next volcanic eruptions may not occur in the same areas, Smith said. Eruptions are hard to predict because they rarely occur in the same spot twice.

Initially, Smith said he did not believe that Yucca Mountain could be in danger of active magma beds. After the recent chemical analyses, he said, "I am slowly coming around to believing in the newer models."

A DOE scientist from the Los Alamos National Laboratory in New Mexico disagreed with Smith.

Frank Perry said that Yucca Mountain is made of volcanic ash layers that are stable and at the deepest level could be a billion years old. At Lunar Crater, the deposits are not the same as evidence from that eruption is younger, he said.